Field
The present disclosure relates to a crystalline form of methyl 2-[(4,6-dimethoxypyrimidin-2-ylcarbamoyl)sulfamoyl]-α-(methanesulfonamido)-p-toluate (mesosulfuron-methyl), to its preparation processes and to its use in agrochemical preparations.
Description of Related Art
Mesosulfuron-methyl, i.e., methyl 2-[(4,6-dimethoxypyrimidin-2-ylcarbamoyl)sulfamoyl]-α-(methanesulfonamido)-p-toluate, is a potent herbicide having high selectivity, high efficiency, low toxicity and other desirable attributes. Mesosulfuron-methyl has molecular formula of C17H21N5O9S2. Its chemical structure is:

It is used post-emergence on crops, such as wheat and cereals, against a variety of annual and perennial grasses and broadleaved weeds. It is rather less toxic towards algae and is of generally low toxicity towards most wildlife.
The commercially available mesosulfuron-methyl, which is usually manufactured by the process described in U.S. Pat. No. 5,648,315 is present in an amorphous state. It has been found that mesosulfuron-methyl in the amorphous state is highly unstable. It will generally undergo significant hydrolysis when dissolved or dispersed in water. Furthermore, hydrolysis can occur during storage, particularly where the compound is exposed to moisture. As a result, the stability of mesosulfuron-methyl is of great concern with respect to providing commercially available formulations. Therefore, there is a need to provide a novel form of mesosulfuron-methyl with increased stability in formulations.